"It's terrible," says Gophen, Hula Committee chairman and an expert in the ecology of the Upper Galilee and the Hula Valley, as he rips a fistful of water lettuce out of a channel. The plant, also known as water cabbage or Nile cabbage, is an invasive species, and scientists do not know how it reached Lake Hula. Now that it has reached the valley's reservoir, which is pumped for irrigation and overflows into Lake Kinneret, Gophen fears the water lettuce could reach the country's most important water source.

"The plant might have come as an indoor aquarium plant, or perhaps was brought by birds," Gophen said. "It's no longer important how it came to be here. All of Lake Kinneret will not be covered with water lettuce, because it cannot grow so densely in open water, but parts of the lake, especially inlets and shallow water, could be covered by the plant. That would severely damage tourism and the pumping stations," Gophen said.

Water lettuce was recently found in a Hula Valley reservoir known as the "operating reservoir." A few days ago, a boat cleared the plant from the surface, but Gophen warns that it could reappear.

However, Lake Hula Park Director Effi Naim is less concerned. "Water lettuce has been growing in the Yesud Hama'aleh channels for at least 10 years, and so far nothing has happened and the plant hasn't reached the Kinneret," he said. Some experts believe the strong winds around the Kinneret will prevent the plant's propagation, and said steps are being taken to thin down the plant and prevent it from reaching the lake.

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